The influence of K2CO3 and KCl on H2 formation during heat treatment of an acid-treated inertinite-rich bituminous coal–char

Abstract

Thermogravimetric-mass spectrometry (TG-MS) studies were conducted in order to investigate the effect of potassium carbonate (K2CO3) and potassium chloride (KCl) on the conversion and hydrogen evolution of chars derived from acid-leached South African inertinite-rich bituminous coal. K2CO3 and KCl (0.5, 1, 3, 5 potassium ion mass percentages) were loaded to the acid-leached (demineralized) coal samples prior to charring. The resulting ‘doped’ coal–char samples were subjected to heat treatment in a CO2 atmosphere up to 1200 °C, and the thermogravimetric curves, as well as the temperature ranges of evolution of hydrogen, were investigated. The results obtained indicate that the temperatures at maximum rate of mass loss (from the DTG curves), as well as the temperatures at maximum rate of hydrogen (H2) evolution (from the MS curves) are lowered with increasing potassium salt loadings. The relative coal gasification reaction reactivity (1/Tmax) determined from the DTG curves increases with increasing potassium salt loading and increases more for K2CO3 than for KCl. The catalytic influence of K2CO3 on the CO2 gasification of the acid-treated coal sample was found to be greater than that of KCl at a loading of 5 % potassium ion mass percentage.